html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
}

header {
  height: 10vh;
  background-color: blanchedalmond;
}
main {
  display: flex;
  height: 80vh;
}
footer {
  height: 10vh;
  background-color: blanchedalmond;
}

header,
footer {
  display: flex;
  align-items: center;
  justify-content: center;
}

.menu,
.content {
  height: 100%;
}
.menu {
  width: 20vw;
  min-width: 200px;
  max-width: 300px;
  background-color: gray;

  display: flex;
  flex-direction: column;
  color: white;
}
.menu .btn {
  flex: 1;

  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0.8;
}
.btn:hover {
  opacity: 1;
  scale: 1.2;
  cursor: pointer;
}
.active {
  scale: 1.2;
  opacity: 1;
}

.content {
  flex-grow: 1;
}
